For a 1522 IP packet with one service tag, the smallest UNI L2 maximum frame size is what?

• A. 1522 IP packet with one service tag
• B. Smallest UNI L2 Max frame size
• C. Maximum frame size
• D. Jumbo frame

Answer: (B)

The concept being tested is ensuring the UNI-L2 boundary can carry the largest frame you’ll encounter. A 1522-byte frame is a standard Ethernet frame with one 802.1Q tag (header plus tag and trailer). To forward such a frame without fragmentation, the UNI’s L2 maximum frame size must be at least 1522 bytes. Therefore, the smallest UNI L2 max frame size that can accommodate this traffic is 1522 bytes, which is captured by the option described as the “Smallest UNI L2 Max frame size.” The other options don’t express that minimum capability: they either reiterate a frame size without tying it to the minimum needed to carry a 1522-byte frame or refer to other concepts (like generic maximum or jumbo frames) that aren’t about the specific minimum requirement here.